From the June 2012 issue

“HDR Toning,” part 2

August 2012: Learn how to tweak the details in your images to achieve a fantastic look.
By | Published: June 25, 2012 | Last updated on May 18, 2023
In my previous column, I went over the basic controls of Adobe Photoshop CS5’s “High Dynamic Range (HDR) Toning.” Now, it’s time to fine-tune.
To fully understand HDR, it helps to know why it was invented. As digital imaging evolved, it became easy to capture information beyond what a single frame can depict. When Photoshop creates a huge 32-bit image — by combining data from the deepest shadows to the brightest highlights — a problem arises. How do you bring all these tonal values down to a more limiting 16- or 8-bit image without losing too much detail? If we could go into this huge image and enhance the local detail elements in it, then when we reduce bit depth (and lose data), the major detail will still be there after the loss.
It turns out this same idea applies to well-made astroimages, which possess good detail from the shadows to the highlights. The better the data you start with, the more “HDR Toning” can do for your image. It will analyze your image and attempt to enhance the subtle detail through the process of “local micro contrast enhancement.” Let’s examine the HDR controls more closely.

First of all, know that whenever you process an astroimage in HDR, the highlights are likely to wash out right away. Not to worry: the “Gamma” and “Highlight” sliders under “Tone and Detail” work well together to bring them back. It’s helpful to have your first step be simply using both sliders to make the highlights look normal again.
The “Radius” setting under “Edge Glow” works similar to the “Radius” setting in “Unsharp Masking,” another image manipulation technique: Selecting smaller pixel amounts emphasizes the fine detail, while working with large numbers of pixels emphasizes the overall image. I usually leave the “Strength” of “Edge Glow” around 0.50, unless the image is unresponsive.

It’s easy to overprocess your photos
with this powerful tool. Your goal is to
maintain the “natural” look of each
image for the best results.

The Horsehead Nebula appears here after basic processing but before “High Dynamic Range (HDR) Toning” (top), after good use of “HDR Toning” (middle), and after too much HDR use. It can be easy to overdo it, leaving an astroimage looking stark and unnatural, but correctly using “HDR Toning” can improve an already great image. Tony Hallas
“Detail” (also under “Tone and Detail”) is like a multiplier of the “Edge Glow” effect. Watch what happens when you set the “Edge Glow” “Radius” slider to different settings while moving the “Detail” slider back and forth. Remember, this is a powerful setting, and it requires discretion. You want to enhance the detail in your image, but not make it obvious how you did it.

Once you are satisfied with your settings, go back and fine-tune the “Gamma” and “Highlight” settings one last time. You want as much “Gamma” (midrange contrast) as your image can support while working in conjunction with the “Highlight” slider to keep the image’s highlights from blowing out.
One of the side effects of “HDR Toning” is emphasizing the noise structure, or visual static, along with the other detail in your image. To fix this, simply use a mild noise reduction application such as Neat Image or Noise Ninja afterward — and possibly before, if your image is noisy to begin with. Excessive noise can “distract” the HDR software from the image’s true tonal values. It bears repeating that it’s easy to overprocess your photos with this powerful tool. Your goal is to maintain the “natural” look of each image for the best results.
“HDR Toning” may seem intimidating at first, but if you experiment with the controls, it will soon start to make sense. (For more details, visit In other words, the best way to understand HDR is to use it!